Fully compensated fluid control valve

Abstract

A direction flow control valve for control of positive and negative loads equipped with a positive and negative load compensator controlled by a single pilot valve stage responsive to positive and negative load pressure signals.

What is claimed is: 
     
       1. A valve assembly supplied with pressure fluid by a pump, said valve assembly comprising a housing having a fluid inlet chamber, a fluid supply chamber, first and second load chambers, and fluid exhaust means connected to reservoir means, first valve means for selectively interconnecting said load chambers with said first supply chamber and said fluid exhaust means, first variable metering orifice means responsive to movement of said first valve means and operable to meter fluid flow between said fluid supply chamber and said load chambers, second variable metering orifice means responsive to movement of said first valve means and operable to meter fluid flow between said load chambers and said fluid exhaust means, positive load fluid throttling means between said fluid inlet chamber and said fluid supply chamber, negative load fluid throttling means between said load chambers and said fluid exhaust means, control means of said positive load and said negative load fluid throttling means having pilot amplifying valve means, said pilot amplifying valve means having first control force generating means responsive to pressure differential across said first variable metering orifice means and second control force generating means responsive to pressure differential across said second variable metering orifice means, said pilot amplifying valve means operable through control of said positive load fluid throttling means to maintain a relatively constant pressure differential across said first variable metering orifice means or through control of said negative load fluid throttling means operable to maintain a relatively constant pressure differential across said second variable metering orifice means. 
     
     
       2. A valve assembly as set forth in claim 1 wherein a spring biasing means opposes said first and said second control force generating means. 
     
     
       3. A valve assembly as set forth in claim 1 wherein said valve assembly has positive load pressure sensing means in said housing selectively communicable with said load chambers, by said first valve means. 
     
     
       4. A valve assembly as set forth in claim 3 wherein said positive load pressure sensing means has means communicable with said pilot amplifying valve means and means operable to transmit positive load pressure signal to said pump. 
     
     
       5. A valve assembly as set forth in claim 1 wherein said valve assembly has negative load pressure sensing means in said housing selectively communicable with said load chambers by said first valve means. 
     
     
       6. A valve assembly as set forth in claim 5 wherein said pilot amplifying valve means has free floating piston means responsive to pressure differential between said fluid supply chamber and said negative load pressure sensing means. 
     
     
       7. A valve assembly as set forth in claim 1 wherein sequencing means connects said positive and negative load fluid throttling means. 
     
     
       8. A valve assembly as set forth in claim 1 wherein said positive load fluid throttling means has fluid isolating means between said fluid inlet chamber and said fluid supply chamber operable to isolate said fluid inlet chamber from said fluid supply chamber when said negative load fluid throttling means throttles fluid flow between one of said load chambers and said fluid exhaust means. 
     
     
       9. A valve assembly as set forth in claim 8 wherein said valve assembly has fluid replenishing means operable to supply fluid flow from said fluid exhaust means to one of said load chambers which is not pressurized when said fluid isolating means isolates said fluid supply chamber from said fluid inlet chamber. 
     
     
       10. A valve assembly as set forth in claim 1 wherein said negative load fluid throttling means is positioned down stream of said second variable metering orifice means. 
     
     
       11. A valve assembly supplied with pressure fluid by a pump, said valve assembly comprising a housing having a fluid inlet chamber, a fluid supply chamber, first and second load chambers, a fluid control chamber, and fluid exhaust means connected to reservoir means, first valve means for selectively interconnecting said load chambers with said fluid supply chamber and said fluid exhaust means, first variable metering orifice means responsive to movement of said first valve means and operable to meter fluid flow between said fluid supply chamber and said load chambers, second variable metering orifice means responsive to movement of said first valve means and operable to meter fluid flow between said load chambers and said fluid exhaust means, second valve means having positive load fluid throttling means between said fluid inlet chamber and said fluid supply chamber, negative load fluid throttling means between said load chambers and said fluid exhaust means, and force generating means responsive to pressure in said fluid control chamber, control means having pilot amplifying valve means, said pilot amplifying valve means having first control force generating means responsive to pressure differential across said first variable metering orifice means, second control force generating means responsive to pressure differential across said second variable metering orifice means, and pressure control means for controlling pressure in said fluid control chamber, said pilot amplifying valve means operable through said pressure control means by controlling pressure in said fluid control chamber to throttling fluid flow by said positive load fluid throttling means to maintain a relatively constant pressure differential across said first variable metering orifice means or to throttle fluid flow by said negative load fluid throttling means to maintain a relatively constant pressure differential across said second variable metering orifice means. 
     
     
       12. A valve assembly as set forth in claim 11 wherein spring biasing means opposes force developed by force generating means of said second valve means. 
     
     
       13. A valve assembly as set forth in claim 11 wherein a spring biasing means opposes said first and said second control force generating means. 
     
     
       14. A valve assembly as set forth in claim 11 wherein said valve assembly has positive load pressure sensing means in said housing selectively communicable with said load chambers, by said first valve means. 
     
     
       15. A valve assembly as set forth in claim 14 wherein said positive load pressure sensing means has means communicable with said pilot amplifying valve means and means operable to transmit positive load pressure signal to said pump. 
     
     
       16. A valve assembly as set forth in claim 11 wherein said valve assembly has negative load pressure sensing means in said housing selectively communicable with said load chambers by said first valve means. 
     
     
       17. A valve assembly as set forth in claim 16 wherein said pilot amplifying valve means has free floating piston means responsive to pressure differential between said fluid supply chamber and said negative load pressure sensing means. 
     
     
       18. A valve assembly as set forth in claim 11 wherein said positive and negative load fluid throttling means are positioned on said second valve means. 
     
     
       19. A valve assembly as set forth in claim 11 wherein said positive load fluid throttling means has fluid isolating means between said fluid inlet chamber and said fluid supply chamber operable to isolate said fluid inlet chamber from said fluid supply chamber when said negative load fluid throttling means throttles fluid flow between one of said load chambers and said fluid exhaust means. 
     
     
       20. A valve assembly as set forth in claim 19 wherein said valve assembly has fluid replenishing means operable to supply fluid flow from said fluid exhaust means to one of said load chambers which is not pressurized when said fluid isolating means isolates said fluid supply chamber from said fluid inlet chamber. 
     
     
       21. A valve assembly as set forth in claim 11 wherein said negative load fluid throttling means is positioned down stream of said second variable metering orifice means. 
     
     
       22. A valve assembly comprising a housing having an inlet chamber connected to a pump and an outlet chamber connected to exhaust means, first valve means operable to selectively communicate said inlet and said outlet chambers with a fluid motor, first control orifice means interposed between said inlet chamber and said fluid motor, second control orifice means interposed between said fluid motor and said outlet chamber, second valve means having positive load fluid throttling means between said inlet chamber and said pump and negative load fluid throttling means between said outlet chamber and said exhaust means, said positive and said negative load fluid throttling means controllable by a pilot valve means and operable either to throttling fluid flow by said positive load fluid throttling means to maintain a constant pressure differential across said first control orifice means or to throttle fluid flow by said negative load fluid throttling means to maintain a constant pressure differential across said second control orifice means. 
     
     
       23. A valve assembly comprising a housing having an inlet chamber connected to a pump and an outlet chamber connected to exhaust means, means operable to selectively communicate said inlet and said outlet chambers with a fluid motor, first control orifice means interposed between said inlet chamber and said fluid motor, second control orifice means interposed between said fluid motor and said exhaust means, positive load fluid throttling means between said inlet chamber and said pump, and negative load fluid throttling means between said outlet chamber and said exhaust means, said positive and said negative load fluid throttling means controllable by a fluid power amplifying and control means and operable either to throttle fluid flow by said positive load fluid throttling means to maintain a relatively constant pressure differential across said first control orifice means or to throttle fluid flow by said negative load fluid throttling means to maintain a relatively constant pressure differential across said second control orifice means. 
     
     
       24. A valve assembly as set forth in claim 23 wherein said fluid power amplifying and control means include pilot amplifying valve means. 
     
     
       25. A valve assembly as set forth in claim 23 wherein said positive load fluid throttling means includes isolating means operable to isolate said pump from said motor when said motor is interconnected with said exhaust means through said negative load fluid throttling means. 
     
     
       26. A valve assembly as set forth in claim 25 wherein fluid replenishing means interconnects for one way fluid flow said fluid motor with said exhaust means when said isolating means isolates said pump from said fluid motor. 
     
     
       27. A valve assembly as set forth in claim 24 wherein said positive load and said negative load fluid throttling means are located on throttling controller means. 
     
     
       28. A valve assembly as set forth in claim 27 wherein said throttling controller means has means responsive to said fluid power amplifying and control means. 
     
     
       29. A valve assembly as set forth in claim 23 wherein fluid power directing means supplies energy to said fluid power amplifying and control means either from said pump or from a negative load supported by said fluid motor. 
     
     
       30. A valve assembly as set forth in claim 29 wherein said fluid power directing means includes check valve logic means.